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The objective of this study was to describe the biology of Sassafras albidum growing on upland hardwood sites in the Ridge and Valley Physiographic Province of Virginia ln an attempt to better understand how this common understory species becomes a dominant vegetative component following clear-felling. Biomass and leaf area regressions were developed using data collected from stems growing on xeric sites (SI₅₀ < 15.2 m) and mesic sites (SI₅₀ > 18.3 m). Due to strong heteroscedasticity in the data, logarithmic allometric equations were found to be the best fitting models. No significant differences were found between biomass equations from the two site qualities. Leaf area regressions were found to be significantly different. Excavations of the root systems of stumps and residual stems found in clear-felled upland hardwood sites indicated that sassafras has a prominent lateral root system. Roots were between 5 and 15 cm in-depth and contained several sprouts. A comparison of the regeneration origin of sassafras stems growing on two sites with differing available soil moisture suggests that root sprouting was the dominant form of regeneration on dry sites, whereas on most sites root sprouting and seedling origin stem were present in equal amount. Root sprouts were significantly larger in size than seedlings. Sex ratio determinations across four site qualities showed a male biased sex ratio. Although sassafras is reported to be delicious, hermaphroditic flowers were found on all sites. Comparison between male and female plants on each site suggest that males have a slight competitive advantage. / Master of Science

Wong, Man Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 149-164). / Abstracts in English and Chinese; appendix in Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iii / Acknowledgements --- p.iv / Table of contents --- p.vi / List of tables --- p.x / List of figures --- p.xii / List of plates --- p.xiv / List of appendices --- p.xv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Study background --- p.1 / Chapter 1.2 --- Conceptual framework of the study --- p.3 / Chapter 1.3 --- Objectives of the study --- p.10 / Chapter 1.4 --- Significance of the study --- p.10 / Chapter Chapter 2 --- Literature Review --- p.12 / Chapter 2.1 --- Overview of world plantations --- p.12 / Chapter 2.2 --- Restoration through the establishment of exotic plantations --- p.13 / Chapter 2.2.1 --- Rationale for restoration --- p.13 / Chapter 2.2.2 --- Restoration principles --- p.14 / Chapter 2.2.3 --- Use of exotic plantations in restoration --- p.15 / Chapter 2.2.4 --- Role of exotic species in plantations --- p.16 / Chapter 2.2.5 --- Problems associated with exotic plantations --- p.18 / Chapter 2.3 --- Transforming exotic woodlands to native forests --- p.21 / Chapter 2.3.1 --- Options of woodland transformation --- p.22 / Chapter 2.3.2 --- Woodland transformation in Hong Kong --- p.26 / Chapter 2.4 --- Summary --- p.28 / Chapter Chapter 3 --- The Study Area --- p.29 / Chapter 3.1 --- Introduction --- p.29 / Chapter 3.2 --- Geological setting of Hong Kong --- p.29 / Chapter 3.2.1 --- Climate --- p.29 / Chapter 3.2.2 --- Geology --- p.30 / Chapter 3.2.3 --- Soils --- p.31 / Chapter 3.2.4 --- Vegetation --- p.32 / Chapter 3.3 --- Study area --- p.33 / Chapter 3.3.1 --- Site selection --- p.33 / Chapter 3.3.2 --- Tai Lam Country Park and characteristics of Acacia confusa plantations --- p.34 / Chapter 3.3.3 --- Site description --- p.35 / Chapter 3.3.4 --- Site management --- p.38 / Chapter 3.3.5 --- Feral cattle disturbance --- p.40 / Chapter Chapter 4 --- Environmental Changes after Clearfelling --- p.41 / Chapter 4.1 --- Introduction --- p.41 / Chapter 4.2 --- Materials and methods --- p.42 / Chapter 4.2.1 --- Instrumentation and microclimatic measurements --- p.42 / Chapter 4.2.2 --- Data processing and statistical analysis --- p.44 / Chapter 4.3 --- Results and discussion --- p.44 / Chapter 4.3.1 --- Solar radiation and temperature after clearfelling --- p.44 / Chapter 4.3.2 --- Relative humidity and wind velocity after clearfelling --- p.48 / Chapter 4.3.3 --- Effect of clearfelling on exotic woodland transformation --- p.52 / Chapter 4.4 --- Summary --- p.53 / Chapter Chapter 5 --- Changes in Soil Properties after Clearfelling --- p.55 / Chapter 5.1 --- Introduction --- p.55 / Chapter 5.2 --- Materials and methods --- p.58 / Chapter 5.2.1 --- Soil sampling --- p.58 / Chapter 5.2.2 --- Laboratory analysis --- p.58 / Chapter 5.2.2.1 --- Texture --- p.59 / Chapter 5.2.2.2 --- Soil reaction pH --- p.59 / Chapter 5.2.2.3 --- Soil organic carbon (SOC) and organic matter (SOM) --- p.59 / Chapter 5.2.2.4 --- Tokal Kjeldahl nitrogen (TKN) --- p.60 / Chapter 5.2.2.5 --- Carbon: nitrogen ratio --- p.60 / Chapter 5.2.2.6 --- Available phosphorus --- p.60 / Chapter 5.2.2.7 --- Exchangeable cations --- p.60 / Chapter 5.2.3 --- Data processing and statistical analysis --- p.61 / Chapter 5.3 --- Results and discussion --- p.61 / Chapter 5.3.1 --- Temporal change of soil texture and reaction pH after clearcutting / Chapter 5.3.2 --- Temporal change of soil organic matter after clearcutting --- p.65 / Chapter 5.3.3 --- Temporal change of Total Kjedahl Nitrogen after clearcutting --- p.69 / Chapter 5.3.4 --- Temporal change of exchangeable cations after clearcutting --- p.71 / Chapter 5.3.5 --- Temporal change of available phosphorus after clearcutting --- p.74 / Chapter 5.3.6 --- Soil nutrient status after clearfelling --- p.76 / Chapter 5.3.7 --- Importance of tree retention on nutrient cycling --- p.78 / Chapter 5.4 --- Summary --- p.80 / Chapter Chapter 6 --- Soil Nitrogen Fluxes after Clearfelling --- p.81 / Chapter 6.1 --- Introduction --- p.81 / Chapter 6.2 --- Materials and methods --- p.83 / Chapter 6.2.1 --- In situ core incubation --- p.84 / Chapter 6.2.2 --- Sampling method --- p.84 / Chapter 6.2.3 --- Laboratory analysis of mineral N --- p.86 / Chapter 6.2.4 --- "Calculation of N mineralization, leaching and uptake" --- p.86 / Chapter 6.2.5 --- Statistical analysis --- p.89 / Chapter 6.3 --- Results and discussion --- p.89 / Chapter 6.3.1 --- Seasonal variation of NH4-N and N03-N --- p.89 / Chapter 6.3.2 --- "Net ammonification, NH4-N leaching and NH4-N uptake" --- p.92 / Chapter 6.3.3 --- "Net nitrification, NO3-N leaching and NO3-N uptake" --- p.94 / Chapter 6.3.4 --- "Net mineralization, leaching and uptake" --- p.95 / Chapter 6.3.5 --- Mineral nitrogen budget --- p.101 / Chapter 6.4 --- Summary --- p.103 / Chapter Chapter 7 --- Growth Performance of Recruited Trees and Restocked Species after Clearfelling --- p.105 / Chapter 7.1 --- Introduction --- p.105 / Chapter 7.2 --- Materials and methods --- p.106 / Chapter 7.2.1 --- Species identification --- p.106 / Chapter 7.2.2 --- Sampling method --- p.106 / Chapter 7.2.3 --- Statistical analysis --- p.107 / Chapter 7.3 --- Results and discussion --- p.107 / Chapter 7.3.1 --- Effect of overstorey removal on the growth of recruited native trees / Chapter 7.3.2 --- Effect of overstorey removal on growth of restocked native seedlings --- p.112 / Chapter 7.3.3 --- Importance of tree retention and seedling restocking in native forest re-establishment --- p.114 / Chapter 7.3.4 --- Species selection for clearcut site --- p.115 / Chapter 7.3.5 --- Browsing damage by feral cattle and its prevention --- p.118 / Chapter 7.4 --- Summary --- p.120 / Chapter Chapter 8 --- Effect of Shade and Water on the Growth of Selected Native Species --- p.121 / Chapter 8.1 --- Introduction --- p.121 / Chapter 8.2 --- Materials and methods --- p.124 / Chapter 8.2.1 --- Study sites --- p.124 / Chapter 8.2.2 --- Experimental design --- p.124 / Chapter 8.2.3 --- Light and water treatments --- p.124 / Chapter 8.2.4 --- Growth performance analysis --- p.126 / Chapter 8.2.5 --- Statistical analysis --- p.127 / Chapter 8.3 --- Results and discussion --- p.127 / Chapter 8.3.1 --- Height growth --- p.127 / Chapter 8.3.2 --- Basal diameter growth --- p.132 / Chapter 8.4 --- Summary --- p.135 / Chapter Chapter 9 --- Conclusions --- p.136 / Chapter 9.1 --- Introduction --- p.136 / Chapter 9.2 --- Summary of major findings --- p.137 / Chapter 9.3 --- Implications of the study --- p.141 / Chapter 9.3.1 --- Transformation of Acacia confusa woodland into native forest by clearfelling --- p.141 / Chapter 9.3.2 --- When and where to undertake clearfelling --- p.144 / Chapter 9.4 --- Limitations of the study --- p.146 / Chapter 9.5 --- Suggestions for further study --- p.147 / References --- p.149 / Appendices --- p.165

Southwestern mixed conifer forests cover approximately 2.5 million acres in Arizona and New Mexico, and provide a wide range of commercial and noncommercial products. The problem is to develop a management prescription which will benefit the greatest mix of resources. An alternatives analysis predicted that a prescription that included small patch clearcutting, in addition to other stand modifications, would meet this criteria. The two Thomas Creek watersheds, in eastern Arizona, were used to validate and test the responses of the forest resources to the preferred prescription, and to increase the understanding of the mixed conifer forest system. The actual harvest created 63 small patch clearcut and group selection openings, averaging 1-2 acres, over 13% of the South Fork watershed. Overall stand density was reduced 34% to 132 square feet per acre. The harvest resulted in significant hydrological changes. Average annual streamflow increased by about 45%, or 1.72 inches, mostly because of increased winter runoff. A greater proportion of the snowmelt generated streamflow occurred earlier in the spring, while annual peak flows were increased by an average of 66%, or about 2.60 cubic feet per second per square mile. The number of days without flow decreased. Average watershed maximum snow water equivalents remained unchanged. The primary causes of the increases were reduced evapotranspiration and increased snow accumulation in the openings; however, it appears that the partially cut stand also contributed to the increases. The treatment benefitted the timber resource. Diameter growth on the South Fork increased for most species compared to the unharvested stand on North Fork. Stand gross growth remained unchanged, but the same volume was being added to fewer trees. The stand, including most openings, is well stocked with adequate numbers of natural and advance regeneration. The Thomas Creek prescription, after 8 years of evaluation, has achieved its objectives of increasing water yields and stand growth while insuring adequate regeneration. It has also benefitted many wildlife species as well as livestock. A similar prescription should increase water yields, by about 15,000 acre-feet annually, from the Upper Black River Basin without adversely impacting other forest resources.

Forest clearance can affect the levels of dissolved organic carbon (DOC), nutrient concentrations and algal biomass in streams, but the possible effect of these inputs on downstream lakes is usually surmised rather than demonstrated. To evaluate the effect of forest clearance on DOC and nutrient cycling in lakes, DOC, total phosphorus (TP), total nitrogen (TN) and chlorophyll (chl a) concentrations were measured in 47 Canadian Shield lakes in Quebec. Of these lakes, 25 were located in drainage basins that were partially clear-cut one to four years previously. In the disturbed sites, an uncut 20-m bufferstrip was left around the lakes and permanent water courses. / To account for differences among the watersheds that are not related to forest harvesting, I also collected a series of catchment and morphometric variables (watershed area, lake area, drainage ratio, forest, wetland, and upstream lake area, watershed slope, water residence time and lake depth). Lake characteristics in undisturbed and disturbed watersheds were compared to determine if forest clearance has a detectable effect on the water quality of downstream lakes. Although comparisons of seasonal and monthly means of the water quality variables between disturbed and reference sites were inconclusive, likely because of high natural variability, the size of the clear-cut was significantly related to means of the water quality characteristics. DOC, TP, TN and chl a increased in lake water with the area of the clear-cuts when large portions of the watershed ($>$50%) were cleared. The results of this study suggest that logging has an effect on water quality and even though a bufferstrip of twenty meters reduces this effect largely, it may not be enough to provide complete protection against the effects of logging activities.

Thirty-eight oligotrophic lakes located around the Reservoir Gouin in central Quebec (48°N, 75°W) were sampled over three years to test the hypothesis that forest clearcutting and fires should be reflected in both higher nutrient export rates and ultimately in greater areal hypolimnetic oxygen deficit rates (AHOD). Significant differences in estimated total phosphorus export rates across treatments were found. However, no effect of clearcutting or forest fire on hypolimnetic oxygen consumption rates could be demonstrated as the result of a much greater and confounding variation in the effect of lake morphometry and the absence of information on the role of catchment-derived organic matter on the AHOD. Consequently, only lake morphometry (hypolimnetic volume to hypolimnetic surface area ratio) served as a predictor of the AHOD. Covariation of mean hypolimnetic water temperature with morphometric variables underlines the influence of lake morphometry on heat dynamics and hypolimnetic respiration rates in these lakes. / This research made considerable use of specialized data manipulation techniques involving a relational database management system, owing to the size of the dataset used (114 lake-years of data). The specific approach used in this thesis is presented in an appendix.

There is a debate about clearcutting versus continuous-cover forestry in Sweden. In other studies forest owners and the general public have been seen to prefer different values. The aim of this study was to compare how members of various associations value clearcutting and continuous-cover forestry due to its effects on environmental-, social- and economical values. And also to understand the members motives for clearcutting and continuous-cover forestry, respectively. Through a web-based questionnaire this study found that members of all associations valued continuous cover forestry the highest, but members of Södra ranked clearcutting almost as high.  It was also found that Södra-members differed by favoring clearcutting, whilst members of Friluftsfrämjandet and Svenska Naturskyddsföreningen instead preferred continuous-cover forestry. Clearcutting had mostly economical motives and continous-cover forestry had mostly environmental- and social motives. This confirms former studies and points out a need for dialogues and exchange of knowledge when striving for sustainable development.

Debris torrents (channelized debris flows) are a geomorphological process only relatively recently recognised in southwest British Columbia. They are of interest both because of the tremendous amount of geomorphic work they do, and because of the hazards they pose to engineering works and residential developments. Fourteen torrents on the east side of Howe Sound, near Vancouver, since October 1981, have claimed twelve lives. Debris torrents differ from water floods in that they involve large amounts of coarse organic and inorganic debris. Therefore, a major requirement for torrent occurrence in a given channel is a supply of mobilizable debris. This thesis examines debris supply mechanisms and rates of debris supply in four small watersheds along Howe Sound, near the village of Lions Bay. An inventory of major debris sources has been compiled, and selected typical sites are examined in detail. Study methods include airphoto interpretation, ground surveying and reconnaissance, field instrumentation and site monitoring, dendrochronology, and materials sampling and testing. Debris supply is controlled by natural factors such as the nature and distribution of the bedrock and surficial materials, topographic gradient, vegetation, weather, and surface and groundwater hydrology, and by human activities such as logging and road construction. A wide variety of debris supply mechanisms operate in the study area, including rockfall and rockslide, talus shift, debris slide, soil wedge failure, ravelling, and snow avalanche. In addition to delivering debris to channel systems, some of these processes are capable of triggering debris torrents. Debris redistribution in channels occurs through debris torrents which do not reach the fans, fluvial processes (bedload transport), and snow avalanches. Active debris removal from main supply points, and storage elsewhere in the channel system, can decrease the frequency but increase the magnitude of torrent events in the basin. The wide variety of debris supply, debris redistribution, and torrent triggering mechanisms acting in this relatively small area points to a need for careful study of individual basins if the torrent potential in an area is to be understood. Regionally-based climatological or hydrological models of torrent occurrence should be employed for preliminary hazard assessment only. / Arts, Faculty of / Geography, Department of / Graduate

This study concerns the alliance against clearcutting that has been formed between the Swedish environmental movement and the Sami movement. Earlier studies on environmentalist/Indigenous alliances have found that such cooperation often has been formed through reproductions of a colonial political relationship, perpetuating Indigenous peoples' structural marginality. This study therefore examines the production of solidarity within this alliance, and attends to how they challenge or reproduce a colonial power asymmetry. The analysis shows that the alliance has formed solidarity over identity and community borders, through conscious commitment to pluralism. This commitment has further shown to rely on the alliance functioning as a site of knowledge-sharing, placing embodied knowledge-practices central to a solidarity production of decolonization. The environmentalists in the alliance have by understanding and recognizing the forests they are seeking to protect as Indigenous land, and as occupied territory central to traditional cultural Indigenous life, enabled a decolonizing reconfiguration of the environment. Notwithstanding, the study problematize certain findings in relation to the risks they demonstrate of reproducing a colonial power asymmetry, and discusses the complexities of environmentalists claiming authority within foreign cultural landscapes, and carrying out protests affecting the social dynamics of Indigenous local communities. / Denna studie rör den allians mot kalhygge som bildats mellan den svenska miljörörelsen och den samepolitiska rörelsen. Tidigare studier om allianser mellan miljöaktivister och urbefolkningar har funnit att sådant samarbete ofta har bildats genom reproduktioner av en kolonial politisk relation, vilket vidmakthåller urbefolkningens strukturella marginalitet. Denna studie undersöker därför produktionen av solidaritet inom denna allians, och utforskar hur de utmanar eller reproducerar en kolonial maktasymmetri. Analysen visar att alliansen skapar solidaritet över identitets- och samhällsgränser, genom ett medvetet engagemang för pluralism. Detta engagemang möjliggörs genom att alliansen fungerar som en plats för kunskapsdelning, vilket placerar förkroppsligade kunskapspraktiker centralt för en solidarisk produktion av avkolonisering. Miljöaktivisterna i alliansen har, genom att förstå och erkänna skogarna som de försöker skydda som ockuperat territorium centralt för traditionellt kulturellt liv, möjliggjort en avkoloniserande omstrukturering av sin framställning av miljön. Studien problematiserar vidare vissa fynd i förhållande till de risker de utgör i att reproducera en kolonial maktsasymmetri, och diskuterar komplexiteten i att miljöaktivister gör anspråk på auktoritet inom främmande kulturlandskap och genomför demonstrationer som påverkar den sociala dynamiken i urbefolkningens lokalsamhällen.

This study examines the effects of clearcut regeneration with whole-tree harvesting on plant diversity. Three approaches were used to study changes in species composition and structure: (1) forest level, (2) stand level, and (3) diversity indices. Within each approach the forest was stratified into three horizontal vegetative regions based upon height: herb (< 1 m), shrub (between 1 and 5 m), and tree (> 5 m). Between the pre-harvest and 17-year-old forest, the relative percent cover of 3 out of 45 herbaceous and 2 out of 34 woody species were found to be significantly different (df = 3; a = 0.10) in the herb stratum; the importance value (average of relative basal area and stem density) of 2 out of 25 woody species in the shrub stratum; and 1 out of 21 woody species in the tree stratum. Within stands, the three lower quality, 17-year-old stands (SI50 = 12.2, 15.2, and 18.3 m) most resembled their pre-harvest composition; however, increases in ericaceous species were observed in the herb and shrub strata potentially inhibit the future regeneration of tree species. The SI50 = 21.3 m stand incurred the greatest changes in composition potentially due to the lack of fire as a disturbance mechanism. The major mechanism that has caused the shifts in species composition and structure is the change in the microenvironment due to the removal of the overstory, which has shifted the competitive advantages from one species to another. In all cases, diversity indices were not found to be significantly different between the 17-year-old and pre-harvest forests. Diversity indices were therefore determined to have limited use if a manager wants to know specific compositions and/or abundance of species. / Master of Science